An Ugnaught appears in both LEGO Star Wars II: The Original Trilogy and LEGO Star Wars: The Complete Saga. Ugnaughts are small character which can crawl through chutes and reach areas which normal characters can't. The Ugnaught has a zapper which can shut off droids.
Ugnaughts live in Cloud City at the planet Bespin and are in charge of destroying droids and turning them into scrap metal. They broke apart C-3PO who had happened upon some Stormtroopers, was sent to their workshop in pieces, and who was rescued and rebuilt (incorrectly) by Chewbacca.